Circular knitting machine



FIG. 1 is a front, top and right side perspective view of a circular knitting machine showing my new design;

FIG. 2 is a bottom and left side perspective view;

FIG. 3 is a top plan view;

FIG. 4 is a front elevational view;

FIG. 5 is a rear elevational view;

FIG. 6 is a bottom plan view;

FIG. 7 is a left side elevational view; and

FIG. 8 is a right side elevational view. 

The ornamental design for a circular knitting machine, substantially as shown. 